The membrane or skin stretched across the end of a drum that produces sound when struck; also used in 'drumhead court-martial'.
Compound: drum + head. Drumhead has been used since the 16th century for the literal membrane, and military courts used 'drumhead' because they were traditionally held around a drum in the field.
A 'drumhead court-martial' meant justice dispensed in the field using a drum as a table—soldiers watched verdicts delivered on the very instrument that announced battle!
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